Dermatome having improved control



Jan 10, 1956 G. J. Hoon DERMATOME HAVING IMPROVED CONTROL Filed Feb. 25, 1954 INVENToR. 612a/ge J. H000 ATTURNEK DERMATOME HAVING IMPROVED CONTROL George J. Hood, Lawrence, Kans.

Application February 23, 1954, Serial No. 411,733

9 Claims. (Cl. 12S-305) rl`his invention relates to improvements in precision instruments and particularly to that class of surgical apparatus now commonly employed to cut skin grafts, the primary object being to improve upon the dermatome disclosed in my U. S. Letters Patent No. 2,288,709, issued July 7, 1942.

It is the most important object of the'present invention to provide a dermatome having improvements affording better control of the instrument during use by the surgeon in cutting a skin graft.

Another important object of the instant invention is to provide a skin cutting instrument permitting more direct control over the rate of cutting.

it is a further important object of the present invention to provide a dermatome wherein the user has exact control of the rate of lifting the skin for cutting so as to afford precise control over the rate of cutting the graft.

Another object of the invention forming the subject matter of this disclosure is to provide in a dermatome having a skin holder, means remote from the axis of rotation of the holder and spaced from the skin upon which the holder is caused to roll for controlling the rate of lifting of the skin so as to produce proper leverage and therefore, more accurate and sensitive control over the rate of cutting.

Still another object of this invention is the provision of a dermatome having mechanism connecting the skin holder with a manual control member for causing the holder to roll along the skin as the control member is manipulated.

An important aim of this invention is the provision of a skin cutting instrument having the aforesaid control member coupled so that it swings with respect to the holder.

Other aims and objects of the instant invention are to provide a dermatome having improved features making possible the cutting of relative large skin grafts, together with the way the control member is operably coupled with a supporting shaft for the skin holder, the manner in which a yoke and handle are utilized as a control member, the way in which the yoke is mounted, the manner of connecting the yoke to the skin holder so as to roll the latter on an area of contact, the manner of providing a convenient rest for the holder, and many more minor objects, all of which will be made clear as the following specification progresses.

in the drawing:

Figure l is a side elevational View of a dermatome having improved control made pursuant to my present invention.

Fig. 2 is a fragmentary, cross-sectionalview taken on irregular line Il-II of Fig. 1.

Fig. 3 is an enlarged, fragmentary, detailed, crosssectional view taken on line III-III of Fig. 2.

Fig. 4 is a fragmentary, detailed, cross-sectional view taken on line IV-IV of Fig. 3; and

Fig. 5 is a viewsimilar to Fig, 1, but showing the skin nited States PatentO holder supported by its three-point rest and the knife bed resting on the control member.

Since the development of the dermatome of my said patent, there has been an ever increasing demand for au instrument thatmakes possible the cutting of even larger skin grafts. As the profession strives toward better and better workmanship, it is desired to eliminate, as much as possible, the unsightly seams usually resulting from patchwork grafting necessitated by the initial cutting of strips of skin that are of relatively small area. Still further, in order to meet the demands of the field, it is necessary to constantly improve upon the dermatome from the standpoint of ease of handling, remembering always that the operation itself is extremely delicate, requiring therefore, accurate and precise control over the instrument by the user if the best end results are to be expected.

The dermatome about to be described is in no sense intended to render the instrument of my prior patent obsolete, nor modify the basic principles therein set down in any way. In fact, reference is had thereto for a full and complete understanding of the present invention. Yet, as will hereinafter appear, the features of the dermatome shown in the accompanying drawing, which improve upon the dermatome of my patent, may well be incorporated therein, and new results, similar to those resulting from the instant invention, will be produced.

The primary component parts of the illustrated instrument consist of a skin holder 10, a control 12, and a cutting assembly 14, the latter of which may take any suitable form and need not diier essentially from the cutting arrangement disclosed in Patent No. 2,288,709 above referred to.

Holder 10 and control 12 are both movable relative to an elongated shaft 16 and the assembly 14 whereas the latter is normally locked rigid to the shaft 16 for movement therewith as a unit. While the holder 10 may take the form shown in my said patent, in the embodiment of the present invention chosen for illustration, it is in the nature of a cylindrical drum, presenting an arcuate wall or arcuate, outermost surface 1S substantially concentric with the shaft 16.

The instrument is condensed without shortening the effective length of holder 10 by insetting a pair of ends 20 and 22 within the holder 10 and securing the same in place in any suitable manner, including use of tie rods 24. Centered bushings 26 carried rigidly by the ends 20 and 22 and slidable longitudinally of shaft 16 rotatably mount holder 10 on shaft 16 and permit free reciprocation of the shaft 16 relative to the holder 10.

Control 12 includes a U-shaped yoke 28 having a pair of legs 30 and 32, embracing the holder 10 and a bight 34 consisting of a plate 38 joining extensions 35 of legs 30 and 32. Legs 30 and 32 may be mounted so as to swing about the longitudinal axis of shaft 16 and relative thereto, as well as to the holder 10 and a frame 48, in any manner but are shown mounted on holder 10 by pivotal connection with bushings 26. This leaves shaft 16 free to reciprocate and yoke 28 free to swing without either adversely affecting the action of the other. A free running fit without undue looseness should be provided for holder 10 between legs 30 and 32. A handle 36 may consist of an elongated tube secured to plate 38 by a bolt 40 joining handle. 36 and plate 38.

Assembly 14 includes a knife or cutter blade 42 mounted on a bed 44 by clip 46. Bed 44 forms the bight of the U-shaped frame 48 having arms 50 attached to the ends of shaft 16. Heads 52 on shaft 16 are eccentric in arms 50 for factory adjustment while eccentric ends 54 on shaft 16 within heads 52 permit adjustment of knife 42 toward and away from surface 18 to determine the thickness of cut. Ay calibrated plate 56- rigid to shaft 16, permits rotation of shaft 16 relative to heads 52, and handles 58 are used when frame 48 is reciprocated, all as morefully explained in my patent abovereferred to. v

Thus, when plate S6 is adjusted to a selected position itcooperates with heads 52 in rigidly securing frame 48 tofshaft 16 for rotation and reciprocation therewith. By virtue of the above construction, handle 36 may be grasped and pulled in the direction of arrow 62 to roll holder 10 along an area of contact 60 in an anticlockwise direction viewing Fig. l, as one of the handles 58 on arms 50 is grasped to reciprocate knife 42 and thereby cut the skin graft. It is understood of course, that adhesive is placed on surface 18 and/or on the skin of the patient to receive the graft as in the method described by said patent. v

Control 12 may also be used to roll holder 10 on the area 60 by connecting yoke 12 to holder 10 in some suitable manner. For example, when a setscrew 64 in leg 30 is brought to bear against end 20, it clamps control 12 to holder 10, thus making it possible to roll holder 10 on the skin area 60 by swinging handle 36 in the direction of the arrow 66, or in the opposite direction. When cutting a graft with control 12 and holder 10 thereby clamped together as a unit, such unit may be rotated about an instantaneous axis or fulcrum in the skin area 60 when handle 36 is swung. The distance of handle 36 from the instantaneous axis of revolution is considerably greater than the distance of the cutting edge from the same axis. A substantial movement of handle 36 is thus required to cause any appreciable amount of rolling of holder 10 and a correspondingly4 slight lifting of the skin into position for cutting. This design thus gives a sensitive and exact control overk the rate of cutting a graft, and such rate of cutting the graft is thus readily controlled by the surgeon.

Alternately, there may be provided a `connection between yoke 28 and holder 10 that releases when handle 36 is swungin the direction of arrow 66. One form `of such connection consists of a pawl 68 swingably carried by leg 32 through a pivot 70. Since end 22 has an outturned flange, holder 10 is provided with an annular, innermost surface 72 engaged by edge 74 of pawl 68.

A spring 76 yieldably holds edge 74 biased against surface 72 and a handle 78 on pawl 68 permits swinging of pawl 68 against the action of spring 76.` A springloaded locking detent 80, reciprocably carried-byV leg 32, fits into cavity 82 in pawl 68 when edge 74 is swung out of engagement with surface 72.

Handle 36 cooperates with a pair of pins 84 on legsY 30-32 to provide a three-point rest for holder 10 as seen in Fig. 5. The pins 84 extend beyond the periphery of holder 10 to permit free rotation thereof when screw 64 is released and pawl 68 held released by detent 80.

Removal of the cut graft and application of cement to surface 18 is facilitated when the dermatome isin the,

position of Fig. 5.

Still further, pins 86 on one or both legs BiO- 32,l

extending oppositely to pins S4, receive bed 44 as shown in Fig. 5 to support frame 48, making adjustment, as well as removal and replacement of blade 42, more convenient. Pins 86 prevent dulling of the knife edge through contact with yoke 32.

It is now seen that better control of the rate of lifting of the skin is provided through greater leverage because of the remoteness of handle 36 from blade 42. The` instrument is in no way too sensitive to slight hand movements to expect the best performance when used by those having minimum experience.

Awkward positions on the part of the surgeon are eliminated, particularly when ratchet means 68 is used while screw 64 is retracted. As soon ashandle 36 has been moved downwardly toward the patient to a positionl where it is no longer convenient to manipulate the instrument and to reciprocate knife 42, handle 36 'may be raised 4 in the direction of arrow 66` to get a new bite so to speak, of as great a magnitude as desired. Spring 76 permits edge 74 of pawl 68 to slide along surface 72 when handle 36 is raised, but when handle 36 is lowered spring 76 causes edge 74 to bite into surface 72 so that holder 10 is rolled along skin area 60 in the direction of arrow 62.

Such swinging movement of control 12 relative to holder 10 gives much better control than through use of a handle adjacent or on the axis of shaft 16 and rigidly connected to holder 10. Screw 64 may be used to keep holder 10 from rotating during such times for instance as when the instrument is disposed in the position shown in Fig. 5.

Finally, the construction above set forth permits increasing the size of holder 10 to permit the cutting of larger grafts and obtaining such grafts from areas otherwise not easily accessible. Splitting of grafts while still adheredto holder 10 is also possible by the setting of blade closer to surface 18, thereby doubling the amount of usable skin to be grafted in place.

Having thus described the invention what is claimed as new and desired to be'secured by Letters Patent is:

1. In a dermatome, a U-shaped frame provided with a cutter blade bed and a pair of arms; an elongated shaft spanning the distance between the arms; a skin holder; a yoke embracing the holder; a handle secured to the yoke; means rotatably mounting the yoke for swinging movement about the longitudinal axis of the shaft, and relative to the shaft, the frame and the holder; means mounting the holder on the shaft for free rotation relative thereto; and means rigidly securing the shaft to the arms whereby the frame and the shaft reciprocate freely as a unit on said longitudinal axis of the shaft relative to the holder and said yoke and swing freely as a unit about said axis of the shaft, said holder having an arcuate surface substantially concentric with the shaft, said yoke having a pair of legs, there being an elongated pin rigid to each leg ofthe yoke respectively, and extending in one direction therefrom, each pin extending beyond said surface of the holder for cooperating with the handle in presenting a three-point rest to support the holder for free rotation on said shaft.

2. In a dermatome-as set forth in claim 1 wherein is provided at least one pin rigid to one of the legs of the yoke and extending in the oppositey direction for supporting the frame when the holder is supported by said threepoint rest.

3. Ina dermatome, a U-shaped frame provided with a cutter blade bed andY a pair of arms; an elongated shaft spanning the distance between the arms; a skin holder; a yoke embracing the holder; means rotatably mounting the yoke for swinging movement about the longitudinal axis of the shaft, and relative to the shaft, the frame and the holder; means mounting the holder on the shaft for free rotation relative thereto; and means rigidly securing the shaft to the arms wherebythe frame and the shaft reciprocate freely as a unit on said longitudinal `axis of the shaft relative to the holder and said yoke and swing freely as a unit about said axis of the shaft, said holder having an arcuate, outermost surface and an innermost arcuate surface, there being means on the yoke engageable with said innermost surface for rolling the holder on an area of contact with said outermost surface upon swinging of the yoke when the dermatome is placed in use.

4. In a dermatome, a U-shaped frame provided with a cutter blade bed and a pair of arms; an elongated shaft spanning the distance between the arms; askin holder; a yoke embracing the holder, means rotatably mounting the yoke for swinging movement about the longitudinal axis of the shaft, and relative to the shaft, the frame and the holder; means mounting the holder on the shaft for free rotation relative thereto; and means rigidly securing the shaft to the arms whereby the frame and the shaft reciprocate freely asa unit on said longitudinal axis of the shaft relative tothe holder and'said yoke and swing freely as a unit about said axis of the shaft, said holder having an arcurate, outermost surface and an innermost arcuate surface, said yoke having a pair of legs, there being means on one leg of the yoke engageable with said innermost surface for rolling the holder on an area of contact with said outermost surface upon swinging of the yoke in one direction when the dermatorne is placed in use.

5. In a dermatome, a U-shaped frame provided with a cutter blade bed and a pair of arms; an elongated shaft spanning the distance between the arms; a skin holder; a yoke embracing the holder; means rotatably mounting the yoke for swinging movement about the longitudinal axis of the shaft, and relative to the shaft, the frame and the holder; means mounting the holder on the shaft for free rotation relative thereto; means rigidly securing the shaft to the arms whereby the frame and the shaft reciprocate freely as a unit on said longitudinal axis of the shaft relative to the holder and said yoke and swing freely as a unit about said axis of the shaft, said holder having an arcuate, outermost surface and an innermost arcuate sur face, there being a pawl engageable with said innermost surface for rolling the holder on an area of contact with said outermost surface upon swinging of the yoke in one direction when the dermatome is placed in use; and means swingably mounting the pawl on the yoke.

6. In a dermatome as set forth in claim wherein is provided a handle on the pawl for swinging the latter out of engagement with said innermost surface.

7. In a dermatome as set forth in claim 5 wherein is provided resilient means interposed between the yoke and said pawl for yieldably holding the pawl biased against said innermost surface.

8. In a dermatorne as set forth in claim 5 wherein is provided a spring-loaded locking detent on said yoke, said pawl having a cavity disposed to receive the detent upon swinging of the pawl out of engagement with said innermost surface.

9. In a dermatome as set forth in claim 8 wherein said holder comprises a cylindrical drum substantially concentric with the shaft, said yoke having a handle and a pair of legs, there being an elongated pin rigid to each leg respectively and extending in one direction therefrom, each pin being longer than the radius of the drum for cooperating with the handle in presenting a three-point rest to support the drum for free rotation on said shaft in either direction when the detent is within the cavity.

References Cited in the le of this patent UNITED STATES PATENTS 2,288,709 Hood July 7, 1942 2,479,260 Reese Aug. 16, 1949 2,590,299 Douglas Mar. 25, 1952 2,636,495 Arden Apr. 28, 1953 

